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The palaeodiet of seven bovids from Makapansgat Limeworks Cave are analysed using dental mesowear. Results suggest that Tragelaphus pricei had a highly attritional diet and was thus a browser. Tragelaphus sp. aff. T. angasii and Aepyceros sp. were also browsers, having diets similar in texture to the extant mule deer (Odocoileus hemionus). Gazella vanhoepeni had an intermediate attrition-abrasion wear signal and groups most closely with extant mixed feeders. Redunca darti and Makapania broomi are at the abrasion end of the wear continuum and cluster with living grazers, such as the hippotragines and reduncines. Parmularius braini had a highly abrasive diet similar to extreme grazers like the American bison (Bison bison) and topi (Damaliscus lunatus). The bovid mesowear data were compared to previous palaeodietary studies using taxonomic uniformitarianism, ecomorphology (hypsodonty), and stable carbon isotopes on the same Makapansgat taxa. This comparison showed that the mesowear results are most closely in-line with the isotope data, both of which are non-genetic signals that reflect diet during an extended portion of an animal's life.

During the last two decades, a broad spectrum of short- and long-term studies on different taxonomic groups has enriched our understanding about how dynamics of taxonomic and ecological diversification have changed through geologic time. There are two major issues that have impacted these studies: the quality and quantity of data used are often insufficient in various ways and the methods used may produce results that are more equivocal than supposed. To investigate these issues more fully, this dissertation focuses on studies on two major aspects: 1) short-term studies examining the nature of successful and unsuccessful predatory attacks on Plio-Pleistocene bivalves; and 2) a Phanerozoic-scale project examining trends in bivalve richness and ecological differentiation. The short-term studies, focusing on shell-breaking predation on bivalves, have shown that the existing methodologies which only study either successful or unsuccessful component of predation in isolation are fraught with potential issues in developing effective interpretations. When these two components (i.e., successful and unsuccessful) are studied in tandem as was done here, however, traces of predation can be used to better constrain potential paleoecological interpretations related to predation intensity, predator's attack strategies, and predator-prey dynamics. The long-term project includes two Phanerozoic studies on bivalves' taxonomic and ecological richness. The taxonomic study has shown how the elements included in various datasets used can affect the Phanerozoic richness trajectory of bivalves. The revised and newly compiled dataset developed here reveals that bivalves showed three major episodes of diversification - a Ordovician radiation of orders and families, a Mesozoic diversification of families, and a dramatic Cenozoic rise in the total number of genera - all of which were synchronous with ecological diversification in terms of appearances of new life forms capable of colonizing new ecospace (i.e., cubes). However, these synchronous changes in taxonomic-ecologic richness were influenced by many biotic (e.g., predation, competition, and adaptive innovations) and abiotic (e.g., nutrient availability, sea level, and temperature) components, for which I propose a multilevel mixed model such that all these components can be studied in tandem.

The West Antarctic Ice Sheet (WAIS) is currently thinning and retreating because shifting oceanic currents are transporting warmer waters to the ice margin, which could lead to a collapse of the ice sheet and global sea level rise. International Ocean Discovery Program (IODP) Expedition 374 sailed to the Ross Sea in 2018 to study the history of the WAIS over the last 20 million years. Previous geologic drilling projects into Ross Sea sediments that record the history of the WAIS (DSDP Leg 28, RISP, MSSTS, Cape Roberts Drilling Project, ANDRILL), as well as modeling studies, show considerable variability of ice-sheet extent during the Neogene and Quaternary including ice sheet collapse during times of extreme warmth. The purpose of this study is to reconstruct paleoenvironments on the Ross Sea and confirm modeling studies that show warming waters in the Southern Ocean led to the loss of Antarctic ice in the past. Site U1523 is a key site as it is located close to the shelf break and therefore sensitive to warm water incursions from modified Circumpolar Deep Water (mCDW) onto the Ross Sea continental shelf as the Antarctic Slope Current weakens with a changing climate. Shelf sites U1522 and U1521 provide perspective for what was happening closer to the Ross Ice Shelf. Multiple incursions of subpolar or temperate planktic foraminifera taxa occurred during the latest Pliocene and early Pleistocene prior to ~1.8 Ma at Site U1523 indicating times of warmer than present conditions and less ice in the Ross Sea. Especially high abundances of foraminifera are recorded in the late Pleistocene associated with Marine Isotope Stage (MIS) 31, MIS 11, and MIS 5e might also indicate reduced ice and relatively warmer conditions. The interval of abundant foraminifera around MIS 31 (MIS 37 to 21) suggests multiple warmer interglacials during the Mid-Pleistocene Transition (MPT). A change in benthic foraminiferal assemblages and a large increase in foraminiferal fragments after the MPT (~800 ka) indicate stronger currents at the seafloor and perhaps corrosive waters, suggesting a major change in water masses entering (mCDW) or exiting the Ross Sea (AABW) since the MPT.

Makapansgat Limeworks Cave is a well-known Australopithecus africanus bearing locality that has spawned a considerable amount of paleoecological research because of its hominin component. Most recently, the paleoecology of this Plio-Pleistocene site has been studied by determining the diet and habitat of other extinct taxa, particularly the bovids. The diets of seven bovids (Aepyceros sp., Gazella vanhoepeni, Makapania broomi, Parmularius braini, Redunca darti, Tragelaphus sp. aff. T. angasii, and Tragelaphus pricei) have now been classified using taxonomic uniformitarianism, ecomorphology, stable carbon isotopes, and mesowear analysis. Here, dental microwear is applied to the same bovids for additional comparison and to further elucidate the strengths and weaknesses of each method. The different dietary proxy methods noted provide a temporal continuum, with genetic signals such as ecomorphology and taxonomic uniformitarianism indicating behavioral adaptations over geologic time, while nongenetic data such as stable carbon isotopes and mesowear reflect different aspects of average diet over extended portions of an animal's life, and dental microwear provides dietary snapshots. Microwear separated an extant baseline of ten bovid species into expected dietary categories and the Makapansgat bovids clearly fell into two groups with the same degree of separation as between extant grazers and browsers. The results indicate that a multidisciplinary approach produces a more accurate and robust reconstruction of past diets. In sum, the microwear analysis is in-line with the isotope and mesowear results, which suggest a stronger browsing component than either taxonomic uniformitarianism or ecomorphology imply.

No / The environmental contexts of the karstic hominin sites in South Africa have been established largely by means of faunal associations; taken together these data suggest a trend from relatively closed and more mesic to open, drier environments from about 3 to 1.5 Ma. Vrba argued for a major shift within this trend ca. 2.4¿2.6 Ma, an influential proposal that posited links between bovid (and hominin) radiation in Africa and the intensification of Northern Hemisphere Glaciation. Yet faunal approaches often rely on habitat and feeding preferences of modern taxa that may differ from those of their extinct predecessors. Here we explore ways of extending 13C/12C data from fossil mammals beyond denoting ¿presence¿ or ¿absence¿ of C4 grasses using the evolution of open environments in South Africa as a case study. To do so we calculated the relative proportions of C3-, mixed-, and C4-feeding herbivores for all the hominin sites for which we have sufficient data based on 13C/12C analyses of fossil tooth enamel. The results confirm a general trend towards more open environments since 3 Ma, but they also emphasize a marked change to open grassy habitats in the latest Pliocene/early Pleistocene. Mean 13C/12C for large felids also mirrored this trend.

abstract: Climate and environmental forcing are widely accepted to be important drivers of evolutionary and ecological change in mammal communities over geologic time scales. This paradigm has been particularly influential in studies of the eastern African late Cenozoic fossil record, in which aridification, increasing seasonality, and C4 grassland expansion are seen as having shaped the major patterns of human and faunal evolution. Despite the ubiquity of studies linking climate and environmental forcing to evolutionary and ecological shifts in the mammalian fossil record, many central components of this paradigm remain untested or poorly developed. To fill this gap, this dissertation employs biogeographical and macroecological analyses of present-day African mammal communities as a lens for understanding how abiotic change may have shaped community turnover and structure in the eastern African Plio-Pleistocene. Three dissertation papers address: 1) the role of ecological niche breadth in shaping divergent patterns of macroevolutionary turnover across clades; 2) the effect of climatic and environmental gradients on community assembly; 3) the relative influence of paleo- versus present-day climates in structuring contemporary patterns of community diversity. Results of these papers call into question many tenets of current theory, particularly: 1) that niche breadth differences (and, by extension, their influence on allopatric speciation) are important drivers of macroevolution, 2) that climate is more important than biotic interactions in community assembly, and 3) that communities today are in equilibrium with present-day climates. These findings highlight the need to critically reevaluate the role and scale-dependence of climate in mammal evolution and community ecology and to carefully consider potential time lags and disequilibrium dynamics in the fossil record. / Dissertation/Thesis / Doctoral Dissertation Anthropology 2018

Os depósitos cenozoicos da Antártica Ocidental, especialmente aqueles da transição Eoceno-Oligoceno, fornecem importantes dados geológicos sobre as mudanças climáticas ocorridas ao longo da Era Cenozoica e de seu impacto na biosfera austral. Assembleias fósseis, incluindo de foraminíferos, foram relatadas para unidades de todas as épocas cenozoicas, em afloramentos dos arquipélagos James Ross e Shetlands do Sul. Todavia, os diamictitos das Formações Hobbs Glacier (Mioceno) e Weddell Sea (Plio-Pleistoceno), que afloram nas ilhas James Ross e Seymour, ainda não haviam sido alvo de análises micropaleontólogicas visando a obtenção de microfósseis com paredes inorgânicas. Foram analisadas amostras de 12 seções estratigráficas da Ilha Seymour, incluindo estratos do topo da Formação La Meseta (Eoceno) e de diversos níveis das formações Hobbs Glacier e Weddell Sea. Pela primeira vez foram encontradas assembleias de microfósseis com paredes inorgânicas, constituídas principalmente por foraminíferos, na porção superior da Formação La Meseta e em estratos das formações Hobbs Glacier e Weddell Sea. Na Formação La Meseta foram encontrados restos autóctones ou parautóctones de foraminíferos Textularia sp., primeira ocorrência do gênero para a unidade. Na Formação Hobbs Glacier, a assembleia autóctone ou parautóctone melhor preservada é composta pelo foraminífero lagenído Oolina stellula e pelo radiolário Larcopyle polyacantha. O foraminífero rotaliído Bolivina sp. é raro e representa um resto alóctone na unidade. Para a Formação Weddell Sea, a assembleia autóctone ou parautóctone melhor preservada é constituída pelo foraminífero lagenído Favulina hexagona e pelo planctônico Globigerinita uvula, além do rotaliído Globocassidulina subglobosa e do radiolário L. polyacantha nos mesmos e em outros níveis. Nos depósitos miocênicos e plio-pleistocênicos ocorrem também foraminíferos aglutinados grandes de táxons típicos de mar profundo, cujas feições tafonômicas indicam sua reelaboração a partir de depósitos mais antigos, possivelmente do Paleoceno, tendo em vista sua associação tafonômica e estratigráfica com o foraminífero Reticulophragmium garcilassoi, um fóssil-índice dessa época. Além de R. garcilassoi, ocorrem outros táxons típicos de assembleias de mar profundo na Formação Hobbs Glacier, como Alveolophragmium orbiculatum, Ammodiscus sp. nov., Ammodiscus pennyi, Ammomarginulina cf. aubertae, Bathysiphon sp. 1, Bathysiphon sp. 2, Cyclammina placenta e Nothia robusta. Na Formação Weddell Sea, as grandes formas aglutinadas são representadas por Ammodiscus sp. nov., Bathysiphon sp. 1, Budashevaella cf. laevigata, Cyclammina cancellata, Glomospira charoides, Saccammina grzybowski, Sculptobaculites barri e Verneulinoides cf. neocomiensis. Alguns táxons da Ilha Seymour podem ser associados àqueles dos depósitos paleocênicos da Nova Zelândia e Nova Guiné, sugerindo alguma correlação cronológica. Embora o registro fossilífero das formações La Meseta, Hobbs Glacier e Weddell Sea seja rarefeito, foi possível identificar restos autóctones ou parautóctones que indicaram a composição parcial das comunidades infaunais e planctônicas que habitavam a região durante a deposição das unidades. Os poucos fósseis-índice encontrados corroboram as idades já propostas paras as formações. Para a Formação Weddell Sea, as assembleias autóctones ou parautóctones e as formas planctônicas permitiram redefinir o contexto deposicional da unidade como glacio-marino, e não plenamente glacial, como anteriormente proposto. / Western Antarctic deposits, especially those from the Eocene-Oligocene transition, provide important geological data on Cenozoic global climate changes and their impact on the southern biota. Fossil assemblages, including foraminifers, are known from geological units from all Cenozoic epochs, in outcrops of the James Ross and South Shetlands archipelagos. However, the diamictites of Hobbs Glacier (Miocene) and Weddell Sea (Plio-Pleistocene) formations, exposed in James Ross and Seymour islands, were never subjects of micropaleontologic analysis targeting inorganic-walled microfossils. Twelve stratigraphic sections on Seymour Island were analyzed, including the top of the La Meseta Formation (Eocene) and several strata of Hobbs Glacier and Weddell Sea formations. Assemblages of inorganic-walled microfossils, composed mainly of foraminifers, were found for the first time in the La Meseta Formation and in strata from the Hobbs Glacier and Weddell Sea formations. Autochthonous or parautochthonous remains of the foraminifer Textularia sp. were found in the La Meseta Formation, being the first occurrence of the genus in this unit. The best preserved autochthonous or parautochthonous assemblage from Hobbs Glacier Formation is composed of the Lagenid foraminifer Oolina stellula and radiolarian Larcopyle polyacantha. The Rotaliid foraminifer Bolivina sp. is rare and represents an allochthonous elements in this formation. In the Weddell Sea Formation, the best preserved autochthonous or parautochthonous assemblage is composed of the Lagenid foraminifer Favulina hexagona and the planktonic Globigerinita uvula, as well as the Rotaliid foraminifer Globocassidulina subglobosa and the radiolarian L. polyacantha in the same and in other strata. In these Miocene and Plio-Pleistocene deposits also occur large agglutinated foraminifers typical of the deep sea, whose taphonomic features indicate their reelaboration from older deposits, possibly from the Paleocene, given their taphonomic and stratigraphic association with the foraminifer Reticulophragmium garcilassoi, a Paleocene index-fossil. Besides R. garcilassoi, other typical deep-sea taxa occur in the Hobbs Glacier Formation, such as Alveolophragmium orbiculatum, Ammodiscus sp. nov., Ammodiscus pennyi, Ammomarginulina cf. aubertae, Bathysiphon sp. 1, Bathysiphon sp. 2, Cyclammina placenta and Nothia robusta. In the Weddell Sea Formation the agglutinated specimens are represented by Ammodiscus sp. nov., Bathysiphon sp. 1, Budashevaella cf. laevigata, Cyclammina cancellata, Glomospira charoides, Saccammina grzybowski, Sculptobaculites barri and Verneulinoides cf. neocomiensis. Some taxa from Seymour Island also occur in the Paleocene deposits of New Zealand and New Guinea, suggesting some chronological correlation. Although the fossil record of the La Meseta, Hobbs Glacier and Weddell Sea formations is sparse, it was possible to identify autochthonous or parautochthonous remains that indicate the partial composition of the infaunal communities and plankton that thrived in the area during the deposition of the units. The few index-fossils found corroborate the ages already indicated for the deposits. For the Weddell Sea Formation, the autochthonous or parautochthonous assemblages and the planktonic specimens allowed the redefinition of its depositional setting as glacial-marine, and not fully glacial, as previously proposed.

The evolutionary history of the South African papionins is a useful analog for the emergence of hominids in South Africa. However, the taxonomic relationships of the papionins are unclear. This study uses low-magnification stereomicroscopy to examine dental microwear and uses the microwear signals to explore the existing classification of these papionins. The results from the species and site level analyses are equivocal. However, the genera and time period results show clear evidence for a dietary change between the extinct and extant forms of Papio and Parapapio. This adds an additional tool for distinguishing these two groups. The dietary changes witnessed in the papionins are likely found in the hominids from the Plio-Pleistocene. Using the papionin analog, hominid dietary evolution may be explored.

Cercopithecoides williamsi, a Plio-Pleistocene primate, is believed to have been a terrestrial colobine monkey. Dental microwear analysis of C. williamsi specimens from South African cave sites was employed to test these assumptions. Analysis of the features shows that although the microwear signature of C. williamsi is similar to that of folivorous primates, there are also similarities with terrestrial papionins. Overall, the dental microwear analysis demonstrates that C. williamsi could have indeed been a folivorous, terrestrial monkey. A high amount of puncture pits also points to a substantial amount of grit in the diet. Similarities between the microwear features of C. williamsi and Cebus apella indicate that fruit or hard objects could have been a supplemental food of C. williamsi. The consumption of underground storage organs covered in grit would explain the heavy pitting of C. williamsi teeth. Being terrestrial, C. williamsi would have been in direct competition with terrestrial papionins.